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            "title": "UTF-8 Validation",
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            "content": "<p>Given an integer array <code>data</code> representing the data, return whether it is a valid <strong>UTF-8</strong> encoding.</p>\n\n<p>A character in <strong>UTF8</strong> can be from <b>1 to 4 bytes</b> long, subjected to the following rules:</p>\n\n<ol>\n\t<li>For a <strong>1-byte</strong> character, the first bit is a <code>0</code>, followed by its Unicode code.</li>\n\t<li>For an <strong>n-bytes</strong> character, the first <code>n</code> bits are all one&#39;s, the <code>n + 1</code> bit is <code>0</code>, followed by <code>n - 1</code> bytes with the most significant <code>2</code> bits being <code>10</code>.</li>\n</ol>\n\n<p>This is how the UTF-8 encoding would work:</p>\n\n<pre>\n<code>   Char. number range  |        UTF-8 octet sequence\n      (hexadecimal)    |              (binary)\n   --------------------+---------------------------------------------\n   0000 0000-0000 007F | 0xxxxxxx\n   0000 0080-0000 07FF | 110xxxxx 10xxxxxx\n   0000 0800-0000 FFFF | 1110xxxx 10xxxxxx 10xxxxxx\n   0001 0000-0010 FFFF | 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx</code>\n</pre>\n\n<p><b>Note: </b>The input is an array of integers. Only the <b>least significant 8 bits</b> of each integer is used to store the data. This means each integer represents only 1 byte of data.</p>\n\n<p>&nbsp;</p>\n<p><strong>Example 1:</strong></p>\n\n<pre>\n<strong>Input:</strong> data = [197,130,1]\n<strong>Output:</strong> true\n<strong>Explanation:</strong> data represents the octet sequence: 11000101 10000010 00000001.\nIt is a valid utf-8 encoding for a 2-bytes character followed by a 1-byte character.\n</pre>\n\n<p><strong>Example 2:</strong></p>\n\n<pre>\n<strong>Input:</strong> data = [235,140,4]\n<strong>Output:</strong> false\n<strong>Explanation:</strong> data represented the octet sequence: 11101011 10001100 00000100.\nThe first 3 bits are all one&#39;s and the 4th bit is 0 means it is a 3-bytes character.\nThe next byte is a continuation byte which starts with 10 and that&#39;s correct.\nBut the second continuation byte does not start with 10, so it is invalid.\n</pre>\n\n<p>&nbsp;</p>\n<p><strong>Constraints:</strong></p>\n\n<ul>\n\t<li><code>1 &lt;= data.length &lt;= 2 * 10<sup>4</sup></code></li>\n\t<li><code>0 &lt;= data[i] &lt;= 255</code></li>\n</ul>\n",
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                    "code": "class Solution {\npublic:\n    bool validUtf8(vector<int>& data) {\n        \n    }\n};",
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                    "code": "class Solution(object):\n    def validUtf8(self, data):\n        \"\"\"\n        :type data: List[int]\n        :rtype: bool\n        \"\"\"\n        ",
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                    "code": "\n\nbool validUtf8(int* data, int dataSize){\n\n}",
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                    "code": "object Solution {\n    def validUtf8(data: Array[Int]): Boolean = {\n        \n    }\n}",
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                    "code": "class Solution {\n    fun validUtf8(data: IntArray): Boolean {\n        \n    }\n}",
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                    "code": "impl Solution {\n    pub fn valid_utf8(data: Vec<i32>) -> bool {\n        \n    }\n}",
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            "hints": [
                "All you have to do is follow the rules. For a given integer, obtain its binary representation in the string form and work with the rules given in the problem.",
                "An integer can either represent the start of a UTF-8 character, or a part of an existing UTF-8 character. There are two separate rules for these two scenarios in the problem.",
                "If an integer is a part of an existing UTF-8 character, simply check the 2 most significant bits of in the binary representation string. They should be <b>10</b>. If the integer represents the start of a UTF-8 character, then the first few bits would be <b>1</b> followed by a <b>0</b>. The number of initial bits (most significant) bits determines the length of the UTF-8 character. \r\n\r\n<br><br>\r\n<b>Note:</b> The array can contain multiple valid UTF-8 characters.",
                "String manipulation will work fine here. But, it is too slow. Can we instead use <b>bit manipulation</b> to do the validations instead of string manipulations?",
                "We can use bit masking to check how many initial bits are set for a given number. <b>We only need to work with the 8 least significant bits as mentioned in the problem.</b>\r\n\r\n<pre>\r\nmask = 1 << 7\r\nwhile mask & num:\r\n    n_bytes += 1\r\n    mask = mask >> 1\r\n</pre>\r\n\r\nCan you use bit-masking to perform the second validation as well i.e. checking if the most significant bit is 1 and the second most significant bit a 0?",
                "To check if the most significant bit is a 1 and the second most significant bit is a 0, we can make use of the following two masks.\r\n\r\n<pre>\r\nmask1 = 1 << 7\r\nmask2 = 1 << 6\r\n\r\nif not (num & mask1 and not (num & mask2)):\r\n    return False\r\n</pre>"
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